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  • Is 'bool' a basic datatype in C++ ?

    - by Naveen
    I got this doubt while writing some code. Is 'bool' a basic datatype defined in the C++ standard or is it some sort of extension provided by the compiler ? I got this doubt because Win32 has 'BOOL' which is nothing but a typedef of long. Also what happens if I do something like this: int i = true; Is it "always" guaranteed that variable i will have value 1 or is it again depends on the compiler I am using ? Further for some Win32 APIs which accept BOOL as the parameter what happens if I pass bool variable?

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  • What to do when using Contract.Assert(true) and the method must return something?

    - by devoured elysium
    I have a bit of code with the following logic: //pseudo-code foreach (element in elementList) { if (element is whatever) return element; } } In theory, there is always one element that is whatever, so this method should pose no problems. In any case, I've put an assertion on the end of the method just to be sure: //pseudo-code foreach (element in elementList) { if (element is whatever) return element; } } Contract.Assert(true, "Invalid state!"); The problem is that as this method has to return something, and the compiler doesn't understand that the assertion will break the program execution. Before using Contracts, in these kind of situations, I used to throw an Exception, which solved the problem. How would you handle this with Contract.Assert()? Returning null or default(element_type) after the Contract.Assert() call knowing it will never be called and shutting up the compiler? Or is there any other more elegant way of doing this? Thanks

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  • auto_inline - inadequate documentation

    - by Mick
    I want to disable inlining for a particular function. What the compiler does for everything else should be as specified in the project properties. I found a page on a forum which suggested the following: #pragma auto_inline(off) void func() { } #pragma auto_inline() The author suggested that calling auto_inline() with no arguments will set the compiler to revert to doing whatever the default action was before the call to auto_inline(off). Can anyone confirm that this works for visual studio 2008? I ask because the VS2008 documentation makes no mention at all of what happens if you call this function with no arguments.

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  • C# overloading with generics: bug or feature?

    - by TN
    Let's have a following simplified example: void Foo<T>(IEnumerable<T> collection, params T[] items) { // ... } void Foo<C, T>(C collection, T item) where C : ICollection<T> { // ... } void Main() { Foo((IEnumerable<int>)new[] { 1 }, 2); } Compiler says: The type 'System.Collections.Generic.IEnumerable' cannot be used as type parameter 'C' in the generic type or method 'UserQuery.Foo(C, T)'. There is no implicit reference conversion from 'System.Collections.Generic.IEnumerable' to 'System.Collections.Generic.ICollection'. If I change Main to: void Main() { Foo<int>((IEnumerable<int>)new[] { 1 }, 2); } It will work ok. Why compiler does not choose the right overload?

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  • C++ Scoping and ambiguity in constructor overloads

    - by loarabia
    I've tried the following code snippet in 3 different compilers (G++, clang++, CL.exe) and they all report to me that they cannot disambiguate the overloaded constructors. Now, I know how I could modify the call to the constructor to make it pick one or the other (either make explicit that the second argument is a unsigned literal value or explicitly cast it). However, I'm curious why the compiler would be attempting to choose between constructors in the first place given that one of the constructors is private and the call to the constructor is happening in the main function which should be outside the class's scope. Can anyone enlighten me? class Test { private: Test(unsigned int a, unsigned int *b) { } public: Test(unsigned int a, unsigned int b) { } }; int main() { Test t1 = Test(1,0); // compiler is confused }

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  • Why not System.Void?

    - by Stewart
    I have no practical reason for knowing this answer, but I'm curious anyway... In C#, trying to use System.Void will produce a compilation error: error CS0673: System.Void cannot be used from C# -- use typeof(void) to get the void type object As I understood it, void is simply an alias of System.Void. So, I don't understand why 'System.Void' can't be used directly as you might with 'string' for 'System.String' for example. I would love to read an explanation for this! Incidentally, System.Void can be successfully used with the Mono compiler, instead of Microsoft's .Net, and there it appears equivalent to using the void keyword. This must therefore be a compiler-enforced restriction rather than a CLR restriction, right?

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  • Stop MSVC++ debug errors from blocking the current process?

    - by Mike Arthur
    Any failed ASSERT statements on Windows cause the below debug message to appear and freeze the applications execution. I realise this is expected behaviour but it is running periodically on a headless machine so prevent the unit tests from failing, instead waiting on user input indefinitely. Is there s a registry key or compiler flag I can use to prevent this message box from requesting user input whilst still allowing the test to fail under ASSERT? Basically, I want to do this without modifying any code, just changing compiler or Windows options. Thanks!

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  • Polymorphic behavior not being implemented

    - by Garrett A. Hughes
    The last two lines of this code illustrate the problem: the compiler works when I use the reference to the object, but not when I assign the reference to an array element. The rest of the code is in the same package in separate files. BioStudent and ChemStudent are separate classes, as well as Student. package pkgPoly; public class Poly { public static void main(String[] arg) { Student[] stud = new Student[3]; // create a biology student BioStudent s1 = new BioStudent("Tom"); // create a chemistry student ChemStudent s2 = new ChemStudent("Dick"); // fill the student body with studs stud[0] = s0; stud[1] = s1; // compiler complains that it can't find symbol getMajor on next line System.out.println("major: " + stud[0].getMajor() ); // doesn't compile; System.out.println("major: " + s0.getMajor() ); // works: compiles and runs correctly } }

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  • .NET CF 2.0: Stream implements IDisposable ... kind of?

    - by mvanbem
    I've run into something odd in a .NET CF 2.0 project for Pocket PC 2003 (Visual Studio 2005). I was dealing with a System.IO.Stream object and found that the IDE wouldn't auto-complete the Dispose() method. I typed it in manually and received: 'System.IO.Stream.Dispose(bool)' is inaccessible due to its protection level The error is referring to the protected Dispose(bool) method. Dispose() is either private or not present. Question 1: How is this possible? Stream implements IDisposable: public abstract class Stream : MarshalByRefObject, IDisposable ... and IDisposable requires a Dispose() method: public interface IDisposable { void Dispose(); } I know the compiler won't let me get away with that in my code. Question 2: Will I cause problems by working around and disposing my streams directly? IDisposable idisp = someStream; idisp.Dispose(); The implicit cast is accepted by the compiler.

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  • Why isn't the new() generic constraint satisfied by a class with optional parameters in the construc

    - by Joshua Flanagan
    The following code fails to compile, producing a "Widget must be a non-abstract type with a public parameterless constructor" error. I would think that the compiler has all of the information it needs. Is this a bug? An oversight? Or is there some scenario where this would not be valid? public class Factory<T> where T : new() { public T Build() { return new T(); } } public class Widget { public Widget(string name = "foo") { Name = name; } public string Name { get; set; } } public class Program { public static void Main() { var widget = new Widget(); // this is valid var factory = new Factory<Widget>(); // compiler error } }

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  • trouble adding a rectange in actionscript

    - by touB
    I have a rectange that I've created and set its individual properties like so var aRect:Rect = new Rect(); aRect.x = 10; aRect.y = 10; aRect.width = "15%"; aRect.height = "15%"; addChild(aRect); I have 2 problems that the compiler seems to be choking on. The first is that the compiler chokes on 15% and "15%", with or without the quotes, neither works. The second is that adding the rectangle doesn't work. I tried all the following, but nothing works. addChild(aRect); Application.addChild(aRect); Application.application.addChild(aRect); stage.addChild(aRect); What's the deal, I thought actionscript would be nicer than mxml.

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  • semicolon in C++?

    - by SysAdmin
    Here is the question Is "missing semicolon" error really required? why not treat it as a warning? Why I am asking this stupid question? When I compile this code int f = 1 int h=2; the compiler intelligently tells me that where I am missing it. but to me its like - "If you know it, just treat it as if its there and go ahead. (Later I can fix the warning) int sdf = 1,df=2; sdf=1 df =2 even for this code it behaves the same. i.e even if multiple statements (without ;) are in the same line, the compiler knows. So, why not just remove this requirement? why not behave like python,vb etc

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  • Can the template parameters of a constructor be explicitly specified?

    - by sth
    A constructor of a class can be a template function. At the point where such a constructor is called, the compiler usually looks at the arguments given to the constructor and determines the used template parameters from them. Is there also some syntax to specify the template parameters explicitly? A contrived example: struct A { template<typename T> A() {} }; Is there a way to instantiate this class? What is the syntax to explicitly specify the constructor's template parameters? My use case would be a problem were the compiler doesn't seem to find the correct templated constructor. Explicitly specifying the template parameters would probably generate more useful error messages or even resolve the problem.

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  • How to define an array inside a function in C?

    - by Arunav Dev
    So in my source file I have the folowin function: void update(state* old_state, state* measurement, uint32_t size) { state new_state[size]; //some function using measurement and old_state and returning the result in newstate arm_fadd_32(measurement,old_state,newstate,size); // rest of the code } Now the compiler throws an error saying that error#28:expression must have a constant value. I think it's due to the fact that even though inside the method the size local variable is not changing the compiler is expecting a constant while defining the size. I have tried the following: int const a = size; and then tried to reinitialize it says constant value is not known. I did some research in internet and it appears that there is no easier way without using malloc, which I don't want to since I am using the code for some embedded application. Is there a way to avoid this problem without really using malloc? Thanks in advance guys!

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  • Passing a generic class to a java function?

    - by rodo
    Is it possible to use Generics when passing a class to a java function? I was hoping to do something like this: public static class DoStuff { public <T extends Class<List>> void doStuffToList(T className) { System.out.println(className); } public void test() { doStuffToList(List.class); // compiles doStuffToList(ArrayList.class); // compiler error (undesired behaviour) doStuffToList(Integer.class); // compiler error (desired behaviour) } } Ideally the List.class and ArrayList.class lines would work fine, but the Integer.class line would cause a compile error. I could use Class as my type instead of T extends Class<List> but then I won't catch the Integer.class case above.

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  • Persistent Logins

    - by Trido
    I am following this article on creating persistent login cookies with my ASP.NET site: http://msdn.microsoft.com/en-us/library/system.web.security.formsauthentication.encrypt.aspx The issue is that when I navigate to the page, I get the following compiler error: Compiler Error Message: CS1061: 'ASP.administration_login_aspx' does not contain a definition for 'Login_Click' and no extension method 'Login_Click' accepting a first argument of type 'ASP.administration_login_aspx' could be found (are you missing a using directive or an assembly reference?) Can anyone tell me why this is. The error message doesn't really say much and I don't believe I am missing a directive or assembly reference. The code builds without any problems. EDIT: I did not include code because I said I was following that link which includes code. I copy/pasted from the example.

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  • Heaps of Trouble?

    - by Paul White NZ
    If you’re not already a regular reader of Brad Schulz’s blog, you’re missing out on some great material.  In his latest entry, he is tasked with optimizing a query run against tables that have no indexes at all.  The problem is, predictably, that performance is not very good.  The catch is that we are not allowed to create any indexes (or even new statistics) as part of our optimization efforts. In this post, I’m going to look at the problem from a slightly different angle, and present an alternative solution to the one Brad found.  Inevitably, there’s going to be some overlap between our entries, and while you don’t necessarily need to read Brad’s post before this one, I do strongly recommend that you read it at some stage; he covers some important points that I won’t cover again here. The Example We’ll use data from the AdventureWorks database, copied to temporary unindexed tables.  A script to create these structures is shown below: CREATE TABLE #Custs ( CustomerID INTEGER NOT NULL, TerritoryID INTEGER NULL, CustomerType NCHAR(1) COLLATE SQL_Latin1_General_CP1_CI_AI NOT NULL, ); GO CREATE TABLE #Prods ( ProductMainID INTEGER NOT NULL, ProductSubID INTEGER NOT NULL, ProductSubSubID INTEGER NOT NULL, Name NVARCHAR(50) COLLATE SQL_Latin1_General_CP1_CI_AI NOT NULL, ); GO CREATE TABLE #OrdHeader ( SalesOrderID INTEGER NOT NULL, OrderDate DATETIME NOT NULL, SalesOrderNumber NVARCHAR(25) COLLATE SQL_Latin1_General_CP1_CI_AI NOT NULL, CustomerID INTEGER NOT NULL, ); GO CREATE TABLE #OrdDetail ( SalesOrderID INTEGER NOT NULL, OrderQty SMALLINT NOT NULL, LineTotal NUMERIC(38,6) NOT NULL, ProductMainID INTEGER NOT NULL, ProductSubID INTEGER NOT NULL, ProductSubSubID INTEGER NOT NULL, ); GO INSERT #Custs ( CustomerID, TerritoryID, CustomerType ) SELECT C.CustomerID, C.TerritoryID, C.CustomerType FROM AdventureWorks.Sales.Customer C WITH (TABLOCK); GO INSERT #Prods ( ProductMainID, ProductSubID, ProductSubSubID, Name ) SELECT P.ProductID, P.ProductID, P.ProductID, P.Name FROM AdventureWorks.Production.Product P WITH (TABLOCK); GO INSERT #OrdHeader ( SalesOrderID, OrderDate, SalesOrderNumber, CustomerID ) SELECT H.SalesOrderID, H.OrderDate, H.SalesOrderNumber, H.CustomerID FROM AdventureWorks.Sales.SalesOrderHeader H WITH (TABLOCK); GO INSERT #OrdDetail ( SalesOrderID, OrderQty, LineTotal, ProductMainID, ProductSubID, ProductSubSubID ) SELECT D.SalesOrderID, D.OrderQty, D.LineTotal, D.ProductID, D.ProductID, D.ProductID FROM AdventureWorks.Sales.SalesOrderDetail D WITH (TABLOCK); The query itself is a simple join of the four tables: SELECT P.ProductMainID AS PID, P.Name, D.OrderQty, H.SalesOrderNumber, H.OrderDate, C.TerritoryID FROM #Prods P JOIN #OrdDetail D ON P.ProductMainID = D.ProductMainID AND P.ProductSubID = D.ProductSubID AND P.ProductSubSubID = D.ProductSubSubID JOIN #OrdHeader H ON D.SalesOrderID = H.SalesOrderID JOIN #Custs C ON H.CustomerID = C.CustomerID ORDER BY P.ProductMainID ASC OPTION (RECOMPILE, MAXDOP 1); Remember that these tables have no indexes at all, and only the single-column sampled statistics SQL Server automatically creates (assuming default settings).  The estimated query plan produced for the test query looks like this (click to enlarge): The Problem The problem here is one of cardinality estimation – the number of rows SQL Server expects to find at each step of the plan.  The lack of indexes and useful statistical information means that SQL Server does not have the information it needs to make a good estimate.  Every join in the plan shown above estimates that it will produce just a single row as output.  Brad covers the factors that lead to the low estimates in his post. In reality, the join between the #Prods and #OrdDetail tables will produce 121,317 rows.  It should not surprise you that this has rather dire consequences for the remainder of the query plan.  In particular, it makes a nonsense of the optimizer’s decision to use Nested Loops to join to the two remaining tables.  Instead of scanning the #OrdHeader and #Custs tables once (as it expected), it has to perform 121,317 full scans of each.  The query takes somewhere in the region of twenty minutes to run to completion on my development machine. A Solution At this point, you may be thinking the same thing I was: if we really are stuck with no indexes, the best we can do is to use hash joins everywhere. We can force the exclusive use of hash joins in several ways, the two most common being join and query hints.  A join hint means writing the query using the INNER HASH JOIN syntax; using a query hint involves adding OPTION (HASH JOIN) at the bottom of the query.  The difference is that using join hints also forces the order of the join, whereas the query hint gives the optimizer freedom to reorder the joins at its discretion. Adding the OPTION (HASH JOIN) hint results in this estimated plan: That produces the correct output in around seven seconds, which is quite an improvement!  As a purely practical matter, and given the rigid rules of the environment we find ourselves in, we might leave things there.  (We can improve the hashing solution a bit – I’ll come back to that later on). Faster Nested Loops It might surprise you to hear that we can beat the performance of the hash join solution shown above using nested loops joins exclusively, and without breaking the rules we have been set. The key to this part is to realize that a condition like (A = B) can be expressed as (A <= B) AND (A >= B).  Armed with this tremendous new insight, we can rewrite the join predicates like so: SELECT P.ProductMainID AS PID, P.Name, D.OrderQty, H.SalesOrderNumber, H.OrderDate, C.TerritoryID FROM #OrdDetail D JOIN #OrdHeader H ON D.SalesOrderID >= H.SalesOrderID AND D.SalesOrderID <= H.SalesOrderID JOIN #Custs C ON H.CustomerID >= C.CustomerID AND H.CustomerID <= C.CustomerID JOIN #Prods P ON P.ProductMainID >= D.ProductMainID AND P.ProductMainID <= D.ProductMainID AND P.ProductSubID = D.ProductSubID AND P.ProductSubSubID = D.ProductSubSubID ORDER BY D.ProductMainID OPTION (RECOMPILE, LOOP JOIN, MAXDOP 1, FORCE ORDER); I’ve also added LOOP JOIN and FORCE ORDER query hints to ensure that only nested loops joins are used, and that the tables are joined in the order they appear.  The new estimated execution plan is: This new query runs in under 2 seconds. Why Is It Faster? The main reason for the improvement is the appearance of the eager Index Spools, which are also known as index-on-the-fly spools.  If you read my Inside The Optimiser series you might be interested to know that the rule responsible is called JoinToIndexOnTheFly. An eager index spool consumes all rows from the table it sits above, and builds a index suitable for the join to seek on.  Taking the index spool above the #Custs table as an example, it reads all the CustomerID and TerritoryID values with a single scan of the table, and builds an index keyed on CustomerID.  The term ‘eager’ means that the spool consumes all of its input rows when it starts up.  The index is built in a work table in tempdb, has no associated statistics, and only exists until the query finishes executing. The result is that each unindexed table is only scanned once, and just for the columns necessary to build the temporary index.  From that point on, every execution of the inner side of the join is answered by a seek on the temporary index – not the base table. A second optimization is that the sort on ProductMainID (required by the ORDER BY clause) is performed early, on just the rows coming from the #OrdDetail table.  The optimizer has a good estimate for the number of rows it needs to sort at that stage – it is just the cardinality of the table itself.  The accuracy of the estimate there is important because it helps determine the memory grant given to the sort operation.  Nested loops join preserves the order of rows on its outer input, so sorting early is safe.  (Hash joins do not preserve order in this way, of course). The extra lazy spool on the #Prods branch is a further optimization that avoids executing the seek on the temporary index if the value being joined (the ‘outer reference’) hasn’t changed from the last row received on the outer input.  It takes advantage of the fact that rows are still sorted on ProductMainID, so if duplicates exist, they will arrive at the join operator one after the other. The optimizer is quite conservative about introducing index spools into a plan, because creating and dropping a temporary index is a relatively expensive operation.  It’s presence in a plan is often an indication that a useful index is missing. I want to stress that I rewrote the query in this way primarily as an educational exercise – I can’t imagine having to do something so horrible to a production system. Improving the Hash Join I promised I would return to the solution that uses hash joins.  You might be puzzled that SQL Server can create three new indexes (and perform all those nested loops iterations) faster than it can perform three hash joins.  The answer, again, is down to the poor information available to the optimizer.  Let’s look at the hash join plan again: Two of the hash joins have single-row estimates on their build inputs.  SQL Server fixes the amount of memory available for the hash table based on this cardinality estimate, so at run time the hash join very quickly runs out of memory. This results in the join spilling hash buckets to disk, and any rows from the probe input that hash to the spilled buckets also get written to disk.  The join process then continues, and may again run out of memory.  This is a recursive process, which may eventually result in SQL Server resorting to a bailout join algorithm, which is guaranteed to complete eventually, but may be very slow.  The data sizes in the example tables are not large enough to force a hash bailout, but it does result in multiple levels of hash recursion.  You can see this for yourself by tracing the Hash Warning event using the Profiler tool. The final sort in the plan also suffers from a similar problem: it receives very little memory and has to perform multiple sort passes, saving intermediate runs to disk (the Sort Warnings Profiler event can be used to confirm this).  Notice also that because hash joins don’t preserve sort order, the sort cannot be pushed down the plan toward the #OrdDetail table, as in the nested loops plan. Ok, so now we understand the problems, what can we do to fix it?  We can address the hash spilling by forcing a different order for the joins: SELECT P.ProductMainID AS PID, P.Name, D.OrderQty, H.SalesOrderNumber, H.OrderDate, C.TerritoryID FROM #Prods P JOIN #Custs C JOIN #OrdHeader H ON H.CustomerID = C.CustomerID JOIN #OrdDetail D ON D.SalesOrderID = H.SalesOrderID ON P.ProductMainID = D.ProductMainID AND P.ProductSubID = D.ProductSubID AND P.ProductSubSubID = D.ProductSubSubID ORDER BY D.ProductMainID OPTION (MAXDOP 1, HASH JOIN, FORCE ORDER); With this plan, each of the inputs to the hash joins has a good estimate, and no hash recursion occurs.  The final sort still suffers from the one-row estimate problem, and we get a single-pass sort warning as it writes rows to disk.  Even so, the query runs to completion in three or four seconds.  That’s around half the time of the previous hashing solution, but still not as fast as the nested loops trickery. Final Thoughts SQL Server’s optimizer makes cost-based decisions, so it is vital to provide it with accurate information.  We can’t really blame the performance problems highlighted here on anything other than the decision to use completely unindexed tables, and not to allow the creation of additional statistics. I should probably stress that the nested loops solution shown above is not one I would normally contemplate in the real world.  It’s there primarily for its educational and entertainment value.  I might perhaps use it to demonstrate to the sceptical that SQL Server itself is crying out for an index. Be sure to read Brad’s original post for more details.  My grateful thanks to him for granting permission to reuse some of his material. Paul White Email: [email protected] Twitter: @PaulWhiteNZ

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  • C#: String Concatenation vs Format vs StringBuilder

    - by James Michael Hare
    I was looking through my groups’ C# coding standards the other day and there were a couple of legacy items in there that caught my eye.  They had been passed down from committee to committee so many times that no one even thought to second guess and try them for a long time.  It’s yet another example of how micro-optimizations can often get the best of us and cause us to write code that is not as maintainable as it could be for the sake of squeezing an extra ounce of performance out of our software. So the two standards in question were these, in paraphrase: Prefer StringBuilder or string.Format() to string concatenation. Prefer string.Equals() with case-insensitive option to string.ToUpper().Equals(). Now some of you may already know what my results are going to show, as these items have been compared before on many blogs, but I think it’s always worth repeating and trying these yourself.  So let’s dig in. The first test was a pretty standard one.  When concattenating strings, what is the best choice: StringBuilder, string concattenation, or string.Format()? So before we being I read in a number of iterations from the console and a length of each string to generate.  Then I generate that many random strings of the given length and an array to hold the results.  Why am I so keen to keep the results?  Because I want to be able to snapshot the memory and don’t want garbage collection to collect the strings, hence the array to keep hold of them.  I also didn’t want the random strings to be part of the allocation, so I pre-allocate them and the array up front before the snapshot.  So in the code snippets below: num – Number of iterations. strings – Array of randomly generated strings. results – Array to hold the results of the concatenation tests. timer – A System.Diagnostics.Stopwatch() instance to time code execution. start – Beginning memory size. stop – Ending memory size. after – Memory size after final GC. So first, let’s look at the concatenation loop: 1: // build num strings using concattenation. 2: for (int i = 0; i < num; i++) 3: { 4: results[i] = "This is test #" + i + " with a result of " + strings[i]; 5: } Pretty standard, right?  Next for string.Format(): 1: // build strings using string.Format() 2: for (int i = 0; i < num; i++) 3: { 4: results[i] = string.Format("This is test #{0} with a result of {1}", i, strings[i]); 5: }   Finally, StringBuilder: 1: // build strings using StringBuilder 2: for (int i = 0; i < num; i++) 3: { 4: var builder = new StringBuilder(); 5: builder.Append("This is test #"); 6: builder.Append(i); 7: builder.Append(" with a result of "); 8: builder.Append(strings[i]); 9: results[i] = builder.ToString(); 10: } So I take each of these loops, and time them by using a block like this: 1: // get the total amount of memory used, true tells it to run GC first. 2: start = System.GC.GetTotalMemory(true); 3:  4: // restart the timer 5: timer.Reset(); 6: timer.Start(); 7:  8: // *** code to time and measure goes here. *** 9:  10: // get the current amount of memory, stop the timer, then get memory after GC. 11: stop = System.GC.GetTotalMemory(false); 12: timer.Stop(); 13: other = System.GC.GetTotalMemory(true); So let’s look at what happens when I run each of these blocks through the timer and memory check at 500,000 iterations: 1: Operator + - Time: 547, Memory: 56104540/55595960 - 500000 2: string.Format() - Time: 749, Memory: 57295812/55595960 - 500000 3: StringBuilder - Time: 608, Memory: 55312888/55595960 – 500000   Egad!  string.Format brings up the rear and + triumphs, well, at least in terms of speed.  The concat burns more memory than StringBuilder but less than string.Format().  This shows two main things: StringBuilder is not always the panacea many think it is. The difference between any of the three is miniscule! The second point is extremely important!  You will often here people who will grasp at results and say, “look, operator + is 10% faster than StringBuilder so always use StringBuilder.”  Statements like this are a disservice and often misleading.  For example, if I had a good guess at what the size of the string would be, I could have preallocated my StringBuffer like so:   1: for (int i = 0; i < num; i++) 2: { 3: // pre-declare StringBuilder to have 100 char buffer. 4: var builder = new StringBuilder(100); 5: builder.Append("This is test #"); 6: builder.Append(i); 7: builder.Append(" with a result of "); 8: builder.Append(strings[i]); 9: results[i] = builder.ToString(); 10: }   Now let’s look at the times: 1: Operator + - Time: 551, Memory: 56104412/55595960 - 500000 2: string.Format() - Time: 753, Memory: 57296484/55595960 - 500000 3: StringBuilder - Time: 525, Memory: 59779156/55595960 - 500000   Whoa!  All of the sudden StringBuilder is back on top again!  But notice, it takes more memory now.  This makes perfect sense if you examine the IL behind the scenes.  Whenever you do a string concat (+) in your code, it examines the lengths of the arguments and creates a StringBuilder behind the scenes of the appropriate size for you. But even IF we know the approximate size of our StringBuilder, look how much less readable it is!  That’s why I feel you should always take into account both readability and performance.  After all, consider all these timings are over 500,000 iterations.   That’s at best  0.0004 ms difference per call which is neglidgable at best.  The key is to pick the best tool for the job.  What do I mean?  Consider these awesome words of wisdom: Concatenate (+) is best at concatenating.  StringBuilder is best when you need to building. Format is best at formatting. Totally Earth-shattering, right!  But if you consider it carefully, it actually has a lot of beauty in it’s simplicity.  Remember, there is no magic bullet.  If one of these always beat the others we’d only have one and not three choices. The fact is, the concattenation operator (+) has been optimized for speed and looks the cleanest for joining together a known set of strings in the simplest manner possible. StringBuilder, on the other hand, excels when you need to build a string of inderterminant length.  Use it in those times when you are looping till you hit a stop condition and building a result and it won’t steer you wrong. String.Format seems to be the looser from the stats, but consider which of these is more readable.  Yes, ignore the fact that you could do this with ToString() on a DateTime.  1: // build a date via concatenation 2: var date1 = (month < 10 ? string.Empty : "0") + month + '/' 3: + (day < 10 ? string.Empty : "0") + '/' + year; 4:  5: // build a date via string builder 6: var builder = new StringBuilder(10); 7: if (month < 10) builder.Append('0'); 8: builder.Append(month); 9: builder.Append('/'); 10: if (day < 10) builder.Append('0'); 11: builder.Append(day); 12: builder.Append('/'); 13: builder.Append(year); 14: var date2 = builder.ToString(); 15:  16: // build a date via string.Format 17: var date3 = string.Format("{0:00}/{1:00}/{2:0000}", month, day, year); 18:  So the strength in string.Format is that it makes constructing a formatted string easy to read.  Yes, it’s slower, but look at how much more elegant it is to do zero-padding and anything else string.Format does. So my lesson is, don’t look for the silver bullet!  Choose the best tool.  Micro-optimization almost always bites you in the end because you’re sacrificing readability for performance, which is almost exactly the wrong choice 90% of the time. I love the rules of optimization.  They’ve been stated before in many forms, but here’s how I always remember them: For Beginners: Do not optimize. For Experts: Do not optimize yet. It’s so true.  Most of the time on today’s modern hardware, a micro-second optimization at the sake of readability will net you nothing because it won’t be your bottleneck.  Code for readability, choose the best tool for the job which will usually be the most readable and maintainable as well.  Then, and only then, if you need that extra performance boost after profiling your code and exhausting all other options… then you can start to think about optimizing.

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  • CodePlex Daily Summary for Sunday, March 06, 2011

    CodePlex Daily Summary for Sunday, March 06, 2011Popular ReleasesIIS Tuner: IIS Tuner 1.0: IIS and ASP.NET performance optimization toolMinemapper: Minemapper v0.1.6: Once again supports biomes, thanks to an updated Minecraft Biome Extractor, which added support for the new Minecraft beta v1.3 map format. Updated mcmap to support new biome format.CRM 2011 OData Query Designer: CRM 2011 OData Query Designer: The CRM 2011 OData Query Designer is a Silverlight 4 application that is packaged as a Managed CRM 2011 Solution. This tool allows you to build OData queries by selecting filter criteria, select attributes and order by attributes. The tool also allows you to Execute the query and view the ATOM and JSON data returned. The look and feel of this component will improve and new functionality will be added in the near future so please provide feedback on your experience. Import this solution int...AutoLoL: AutoLoL v1.6.4: It is now possible to run the clicker anyway when it can't detect the Masteries Window Fixed a critical bug in the open file dialog Removed the resize button Some UI changes 3D camera movement is now more intuitive (Trackball rotation) When an error occurs on the clicker it will attempt to focus AutoLoLYAF.NET (aka Yet Another Forum.NET): v1.9.5.5 RTW: YAF v1.9.5.5 RTM (Date: 3/4/2011 Rev: 4742) Official Discussion Thread here: http://forum.yetanotherforum.net/yaf_postsm47149_v1-9-5-5-RTW--Date-3-4-2011-Rev-4742.aspx Changes in v1.9.5.5 Rev. #4661 - Added "Copy" function to forum administration -- Now instead of having to manually re-enter all the access masks, etc, you can just duplicate an existing forum and modify after the fact. Rev. #4642 - New Setting to Enable/Disable Last Unread posts links Rev. #4641 - Added Arabic Language t...Snippet Designer: Snippet Designer 1.3.1: Snippet Designer 1.3.1 for Visual Studio 2010This is a bug fix release. Change logFixed bug where Snippet Designer would fail if you had the most recent Productivity Power Tools installed Fixed bug where "Export as Snippet" was failing in non-english locales Fixed bug where opening a new .snippet file would fail in non-english localesChiave File Encryption: Chiave 1.0: Final Relase for Chave 1.0 Stable: Application for file encryption and decryption using 512 Bit rijndael encyrption algorithm with simple to use UI. Its written in C# and compiled in .Net version 3.5. It incorporates features of Windows 7 like Jumplists, Taskbar progress and Aero Glass. Now with added support to Windows XP! Change Log from 0.9.2 to 1.0: ==================== Added: > Added Icon Overlay for Windows 7 Taskbar Icon. >Added Thumbnail Toolbar buttons to make the navigation easier...DotNetNuke® Community Edition: 05.06.02 Beta: Major HighlightsFixed issue where "My Folder" was not available in the URL control and the Telerik HTML Editor Fixed issue where HTML Editor dialogs were not displaying correctly in alternate languages Fixed issue with Regex for email validation Fixed race condition in the core scheduler Fixed issue where editing Host page settings would result in broken host menu Fixed issue where "Apply to All Modules" setting was not propogating settings correctly. Fixed issue where browser lan...DirectQ: Release 1.8.7 (RC1): Release candidate 1 of 1.8.7GoogleTrail: TrailMap Beta 1: Trailmap beta 1 release Now we have updated custom map builder. Now we have complete gpx file editor. Now we have elevation data update service for any gpx file. (currently supports only google only).Chirpy - VS Add In For Handling Js, Css, DotLess, and T4 Files: Margogype Chirpy (ver 2.0): Chirpy loves Americans. Chirpy hates Americanos.ASP.NET: Sprite and Image Optimization Preview 3: The ASP.NET Sprite and Image Optimization framework is designed to decrease the amount of time required to request and display a page from a web server by performing a variety of optimizations on the page’s images. This is the third preview of the feature and works with ASP.NET Web Forms 4, ASP.NET MVC 3, and ASP.NET Web Pages (Razor) projects. The binaries are also available via NuGet: AspNetSprites-Core AspNetSprites-WebFormsControl AspNetSprites-MvcAndRazorHelper It includes the foll...Sandcastle Help File Builder: SHFB v1.9.2.0 Release: This release supports the Sandcastle June 2010 Release (v2.6.10621.1). It includes full support for generating, installing, and removing MS Help Viewer files. This new release is compiled under .NET 4.0, supports Visual Studio 2010 solutions and projects as documentation sources, and adds support for projects targeting the Silverlight Framework. NOTE: The included help file and the online help have not been completely updated to reflect all changes in this release. A refresh will be issue...Network Monitor Open Source Parsers: Microsoft Network Monitor Parsers 3.4.2554: The Network Monitor Parsers packages contain parsers for more than 400 network protocols, including RFC based public protocols and protocols for Microsoft products defined in the Microsoft Open Specifications for Windows and SQL Server. NetworkMonitor_Parsers.msi is the base parser package which defines parsers for commonly used public protocols and protocols for Microsoft Windows. In this release, we have added 4 new protocol parsers and updated 79 existing parsers in the NetworkMonitor_Pa...Image Resizer for Windows: Image Resizer 3 Preview 1: Prepare to have your minds blown. This is the first preview of what will eventually become 39613. There are still a lot of rough edges and plenty of areas still under construction, but for your basic needs, it should be relativly stable. Note: You will need the .NET Framework 4 installed to use this version. Below is a status report of where this release is in terms of the overall goal for version 3. If you're feeling a bit technically ambitious and want to check out some of the features th...JSON Toolkit: JSON Toolkit 1.1: updated GetAllJsonObjects() method and GetAllProperties() methods to JsonObject and Properties propertiesFacebook Graph Toolkit: Facebook Graph Toolkit 1.0: Refer to http://computerbeacon.net for Documentation and Tutorial New features:added FQL support added Expires property to Api object added support for publishing to a user's friend / Facebook Page added support for posting and removing comments on posts added support for adding and removing likes on posts and comments added static methods for Page class added support for Iframe Application Tab of Facebook Page added support for obtaining the user's country, locale and age in If...ASP.NET MVC Project Awesome, jQuery Ajax helpers (controls): 1.7.1: A rich set of helpers (controls) that you can use to build highly responsive and interactive Ajax-enabled Web applications. These helpers include Autocomplete, AjaxDropdown, Lookup, Confirm Dialog, Popup Form, Popup and Pager small improvements for some helpers and AjaxDropdown has Data like the Lookup except it's value gets reset and list refilled if any element from data gets changedManaged Extensibility Framework: MEF 2 Preview 3: This release aims .net 4.0 and Silverlight 4.0. Accordingly, there are two solutions files. The assemblies are named System.ComponentModel.Composition.Codeplex.dll as a way to avoid clashing with the version shipped with the 4th version of the framework. Introduced CompositionOptions to container instantiation CompositionOptions.DisableSilentRejection makes MEF throw an exception on composition errors. Useful for diagnostics Support for open generics Support for attribute-less registr...PHPExcel: PHPExcel 1.7.6 Production: DonationsDonate via PayPal via PayPal. If you want to, we can also add your name / company on our Donation Acknowledgements page. PEAR channelWe now also have a full PEAR channel! Here's how to use it: New installation: pear channel-discover pear.pearplex.net pear install pearplex/PHPExcel Or if you've already installed PHPExcel before: pear upgrade pearplex/PHPExcel The official page can be found at http://pearplex.net. Want to contribute?Please refer the Contribute page.New Projectsasp.net mvc 3 simple cms: asp.net mvc3 cms for learling purpose.C++ Mini Framework: C++ Mini Framework is a simple and easy to use class library in source format to quickly do things you commonly need to do in native projects with the purpose to get you started specifically targeting new C++ developers hopping you will be productive from the very start.Community Megaphone Helpers: Community Megaphone Helpers is a project intended as a means of sharing and accepting contributions for reusable Razor helper modules for functionality used in the Community Megaphone events web application, including Bing maps and more. Supports Microsoft WebMatrix & MVC 3CRM 2011 OData Query Designer: The CRM 2011 OData Query Designer is a Silverlight 4 application that is packaged as a Managed CRM 2011 Solution. The tool allows you to build OData REST queries by selecting filter criteria, select attributes and order by attributes. The tool also allows you to Execute the queryFaceted Search: Implementation of faceted (advanced) search with composite client side UI. Abstraction interfaces for intagration with different server side technologies, implementation for ASP.NET MVC. FileRenamePro: FileRenamePro makes it easier for users to rename files using advanced rules and regular expressions. It's developed in C#.GT5 Mobile: Gran-Turismo Remote Racing mobile site wrapper.KAT: KAT - Knowledge Assessment Tool is a Solution from IndERP in order to automate Performance and Process Management for a Technology/Job Oriented Companies. monopoly game: Monopoly is an open source project for educational purposes. The project will incorporate XNA, Silverlight, WCF technologies. The project will also show good design patterns considerations, and integration into Facebook App. The project will be written in C#.MuDB: MuDB is an embedded object-oriented database for the .NET Micro Framework which provides a simple yet useful interface for managing data.NDataStructure: A library providing a handful of useful data structures omitted from the .NET framework.Set NuGet version number: A simple command line tool that makes it easy to set the version number within a NuGet .nuspec package configuration file. This is useful for when you want to automatically update and publish a NuGet package from your build system.Sightreader: Small application to aid in the wrote learning of basic musical notation.SSAS Operations Templates: SSAS Operations Templates includes SSIS packages, scripts and code samples for automating maintenance of SSAS in a production environment. Includes operations such as backup the current state of cube designs in production, scripting paritition creation, etc.Team Run Log: Team Run LogTEDHelper: Download TED movie's subtitle. ?? TED ?????。testprojectit339: project339Ultimate Resume Repository: A class library and application for storing resumes of multiple people with the ability to export a targeted resume in various, configurable formats. Further additions may include cover letters, browser add-ons to populate applications, job search engine integration, etc...Umbraco: Inspired DataTypes: New datatypes that are not in the default install to make Umbraco have some new controls such as Content/Media Treeview, Content/Media Drop Down List with Treeview. Controls have options to restrict DocumentTypes or MediaType and the start location to retreive fromUsing different schemas in the same Orchestration Receive Port: Using different schemas in the same Orchestration Receive PortWF4Host: Examples in re-hosting Workflow 4 designer.WMP Hotkeys: WMP Hotkeys is a windows media player plugin that enable users to use VLC player like keyboard shortcuts(e.g SPACE to play/pause) in Windows Media Player.

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  • CodePlex Daily Summary for Tuesday, December 11, 2012

    CodePlex Daily Summary for Tuesday, December 11, 2012Popular ReleasesDirectX Tool Kit: December 11, 2012: December 11, 2012 Ex versions of DDSTextureLoader and WICTextureLoader Removed use of ATL's CComPtr in favor of WRL's ComPtr for all platforms to support VS Express editions Updated VS 2010 project for official 'property sheet' integration for Windows 8.0 SDK Minor fix to CommonStates for Feature Level 9.1 Tweaked AlphaTestEffect.cpp to work around ARM NEON compiler codegen bug Added dxguid.lib as a default library for Debug builds to resolve GUID link issuesCleverBobCat: CleverBobCat 1.1.3: Fixed: - Cart code now works in vab, wheels retract correctly and no more anchors visible - No more exceptions on VAB Added: - ResourceTransfer beam now has a wide array of configurable options for beam material, size and colors - Added an optional offset to resource transfer, if specificed the "beam" will start from part center + the specified offsetSharpCompress - a fully native C# library for RAR, 7Zip, Zip, Tar, GZip, BZip2: SharpCompress 0.8.2: This release just contains some fixes that have been done since the last release. Plus, this is strong named as well. I apologize for the lack of updates but my free time is less these days.re-linq: 1.13.178.0: This is build 1.13.178.0 of re-linq. Find the complete release notes for the build here: Release NotesMedia Companion: MediaCompanion3.511b release: Two more bug fixes: - General Preferences were not getting restored - Fanart and poster image files were being locked, preventing changes to themVodigi Open Source Interactive Digital Signage: Vodigi Release 5.5: The following enhancements and fixes are included in Vodigi 5.5. Vodigi Administrator - Manage Music Files - Add Music Files to Image Slide Shows - Manage System Messages - Display System Messages to Users During Login - Ported to Visual Studio 2012 and MVC 4 - Added New Vodigi Administrator User Guide Vodigi Player - Improved Login/Schedule Startup Procedure - Startup Using Last Known Schedule when Disconnected on Startup - Improved Check for Schedule Changes - Now Every 15 Minutes - Pla...Secretary Tool: Secretary Tool v1.1.0: I'm still considering this version a beta version because, while it seems to work well for me, I haven't received any feedback and I certainly don't want anyone relying solely on this tool for calculations and such until its correct functioning is verified by someone. This version includes several bug fixes, including a rather major one with Emergency Contact Information not saving. Also, reporting is completed. There may be some tweaking to the reporting engine, but it is good enough to rel...VidCoder: 1.4.10 Beta: Added progress percent to the title bar/task bar icon. Added MPLS information to Blu-ray titles. Fixed the following display issues in Windows 8: Uncentered text in textbox controls Disabled controls not having gray text making them hard to identify as disabled Drop-down menus having hard-to distinguish white on light-blue text Added more logging to proxy disconnect issues and increased timeout on initial call to help prevent timeouts. Fixed encoding window showing the built-in pre...WPF Application Framework (WAF): WPF Application Framework (WAF) 2.5.0.400: Version 2.5.0.400 (Release): This release contains the source code of the WPF Application Framework (WAF) and the sample applications. Requirements .NET Framework 4.0 (The package contains a solution file for Visual Studio 2010) The unit test projects require Visual Studio 2010 Professional Changelog Legend: [B] Breaking change; [O] Marked member as obsolete Update the documentation. InfoMan: Write the documentation. Other Downloads Downloads OverviewHome Access Plus+: v8.5: v8.5.1211.1240 Fixed: changed to using the thumbnailPhoto attribute instead of jpegPhoto v8.5.1208.1500 This is a point release, for the other parts of HAP+ see the v8.3 release. Fixed: #me#me issue with the Edit Profile Link Updated: 8.5.1208 release Updated: Documentation with hidden booking system feature Added: Room Drop Down to the Booking System (no control panel interface), can be Resource Specific Fixed: Recursive AD Group Membership Lookup Fixed: User.IsInRole with recursive lookup...Http Explorer: httpExplorer-1.1: httpExplorer now has the ability to connect to http server via web proxies. The proxy may be explicitly specified by hostname or IP address. Or it may be specified via the Internet Options settings of Windows. You may also specify credentials to pass to the proxy if the proxy requires them. These credentials may be NTLM or basic authentication (clear text username and password).Bee OPOA Platform: Bee OPOA Demo V1.0.001: Initial version.Microsoft Ajax Minifier: Microsoft Ajax Minifier 4.78: Fix for issue #18924 - using -pretty option left in ///#DEBUG blocks. Fix for issue #18980 - bad += optimization caused bug in resulting code. Optimization has been removed pending further review.Dynamics Crm 2011 Solution Manager: Crm Solution Manager 1.0: First Version.Lava JS: Lava JS 1.0: Sourcemp3player-xslt-plugin: mp3player module 1.0: This is a mp3 player module that you can install on your umbraco project. It can display the list of the media and you can click the button to play or stop.STeaL : stealed functionarities from STL: STeaL 0.4.1(prelerease): + fill / fill-nMi-DevEnv: Development 0.5: Ran a new test scenario where I created a DC, then created a web server, blew it away, then re-created the web server. The purpose of the test was to see how the installers would handle information existing in AD, like the OU for CRM. This revealed yet another silly issue in retrieving details of existing OU's, where I had the syntax wrong. I should read exception details more closely :) Apologies also, I've just now started labelling the solution according to these "snapshots". Sorry for...Yahoo! UI Library: YUI Compressor for .Net: Version 2.2.0.0 - Epee: New : Web Optimization package! Cleaned up the nuget packages BugFix: minifying lots of files will now be faster because of a recent regression in some code. (We were instantiating something far too many times).DtPad - .NET Framework text editor: DtPad 2.9.0.40: http://dtpad.diariotraduttore.com/files/images/flag-eng.png English + A new built-in editor for the management of CSV files, including the edit of cells, deleting and adding new rows, replacement of delimiter character and much more (issue #1137) + The limit of rows allowed before the decommissioning of their side panel has been raised (new default: 1.000) (issue #1155, only partially solved) + Pressing CTRL+TAB now DtPad opens a screen that shows the list of opened tabs (issue #1143) + Note...New ProjectsAmazon S3 Upload with Uploadify: ASP.MVC upload file from client browser direct to Amazon S3Ameoto DEV: Bin for all of our software sources :DAutonomic Computing Library: This framework will simplify the development of Autonomic Computing Systems. BIUUITest: BIUUITestBotvaBot: This project should help tothe Botva.Ru gamers to automize their game proces. It is a set of libraries for simple sending of the HTTP requests with list of the main requests to the botva.ru web-site. Also project contains the clients forsimple using this request umulators.Cartellino: Scopo del progetto è la realizzazione di un software in grado di rilevare i dati dai rilevatori 3Tec (www.3tec.it) e stampare i cartellini presenza dei dipendenticmsforbeginner: in this project explain how to edit, create multiple webpages to a single website with less knowledge on html ,.net languagesContact Us Module: This is an Umbraco based module for feedback. You can upload the contact us module in the dashboard and then display those module anywhere in your site.CrmXpress Security Roles Helper For Microsoft Dynamics CRM 2011: CrmXpress Security Roles Helper is a tool/utility. It lets you compare the Security Roles for their differences at the privilege level with their scopes.DarkSky Helpdesk: DarkSky Helpdesk is an Orchard module that turns your Orchard application into a Helpdesk system.DataEntity: A Framework that help us to make persistences and materializations from any SQLServer DataBase Tables to Entity classes. Better performance with native ADO.NET.Edisfera DNN Training Task Module: This is a training project to familiarize with codeplex and dnn module creation.eyoung events description language: Eyoung is a event driven language. It can be used in many fields, such as intrusion action definition.FastBuild: Fast build VS2010 C++ project with the options OpenCV, QT, Boost and OpenGL.Find Changeset By Comment: This extension is used to find changesets that contain a specific phrase in a comment.Gatepass System: This application under development is my first application on codeplex. It is meant primarily as a learning tool while developing a Gatepass System. This GateHandle Template Library (HTL): Handle Template Library (HTL) is a C++ library for developing Windows applications and services. It provides a set of classes for files, threads, events, and more.iDoklad API: iDoklad API Demo je Open Source projekt spolecnosti Cígler Software. Ukázková aplikace demonstruje napojení na fakturacní službu iDokladIronBefunge: IronBefunge is an interpretor (written in .NET) for Befunge programs.Iterator Tasks: Iterator Tasks is a iterator-based coroutine class library.Javacc-Compile-N14: Javacc - compile - N14 is a students' compiler project and we use javacc to compiler XYZ-2 languageMessenger Game - Starter Kit: Kom godt i gang med at lave spil til Messenger med dette komplette Starter Kit. Indeholder et komplet netværksspil lavet med Messenger Activity API og Silverlight.MOBZcript: MOBZcript is a simple batch file editor for cmd scripts. It saves and runs your scripts as if you started them from a command line.NET.Library: The NET.Library will be available in different versions to run on the .Net 2, 3 and 4 frameworks and consists of various .Net programming utilities. proxificator: Proxificator is component for getting the appropriate proxyRetailManagement: abcStudentManage: testWebQQ Interface: A library that enable programmers to access QQ much easier via codeZytonic Screenshot: Upload Images From your Computer Harddrive or Screen With Ease!

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  • How do I get confidence intervals without inverting a singular Hessian matrix?

    - by AmalieNot
    Hello. I recently posted this to reddit and it was suggested I come here, so here I am. I'm a student working on an epidemiology model in R, using maximum likelihood methods. I created my negative log likelihood function. It's sort of gross looking, but here it is: NLLdiff = function(v1, CV1, v2, CV2, st1 = (czI01 - czV01), st2 = (czI02 - czV02), st01 = czI01, st02 = czI02, tt1 = czT01, tt2 = czT02) { prob1 = (1 + v1 * CV1 * tt1)^(-1/CV1) prob2 = ( 1 + v2 * CV2 * tt2)^(-1/CV2) -(sum(dbinom(st1, st01, prob1, log = T)) + sum(dbinom(st2, st02, prob2, log = T))) } The reason the first line looks so awful is because most of the data it takes is inputted there. czI01, for example, is already declared. I did this simply so that my later calls to the function don't all have to have awful vectors in them. I then optimized for CV1, CV2, v1 and v2 using mle2 (library bbmle). That's also a bit gross looking, and looks like: ml.cz.diff = mle2 (NLLdiff, start=list(v1 = vguess, CV1 = cguess, v2 = vguess, CV2 = cguess), method="L-BFGS-B", lower = 0.0001) Now, everything works fine up until here. ml.cz.diff gives me values that I can turn into a plot that reasonably fits my data. I also have several different models, and can get AICc values to compare them. However, when I try to get confidence intervals around v1, CV1, v2 and CV2 I have problems. Basically, I get a negative bound on CV1, which is impossible as it actually represents a square number in the biological model as well as some warnings. The warnings are this: http://i.imgur.com/B3H2l.png . Is there a better way to get confidence intervals? Or, really, a way to get confidence intervals that make sense here? What I see happening is that, by coincidence, my hessian matrix is singular for some values in the optimization space. But, since I'm optimizing over 4 variables and don't have overly extensive programming knowledge, I can't come up with a good method of optimization that doesn't rely on the hessian. I have googled the problem - it suggested that my model's bad, but I'm reconstructing some work done before which suggests that my model's really not awful (the plots I make using the ml.cz.diff look like the plots of the original work). I have also read the relevant parts of the manual as well as Bolker's book Ecological Models in R. I have also tried different optimization methods, which resulted in a longer run time but the same errors. The "SANN" method didn't finish running within an hour, so I didn't wait around to see the result. tl;dr : my confidence intervals are bad, is there a relatively straightforward way to fix them in R. My vectors are: czT01 = c(5, 5, 5, 5, 5, 5, 5, 25, 25, 25, 25, 25, 25, 25, 50, 50, 50, 50, 50, 50, 50) czT02 = c(5, 5, 5, 5, 5, 10, 10, 10, 10, 10, 25, 25, 25, 25, 25, 50, 50, 50, 50, 50, 75, 75, 75, 75, 75) czI01 = c(25, 24, 22, 22, 26, 23, 25, 25, 25, 23, 25, 18, 21, 24, 22, 23, 25, 23, 25, 25, 25) czI02 = c(13, 16, 5, 18, 16, 13, 17, 22, 13, 15, 15, 22, 12, 12, 13, 13, 11, 19, 21, 13, 21, 18, 16, 15, 11) czV01 = c(1, 4, 5, 5, 2, 3, 4, 11, 8, 1, 11, 12, 10, 16, 5, 15, 18, 12, 23, 13, 22) czV02 = c(0, 3, 1, 5, 1, 6, 3, 4, 7, 12, 2, 8, 8, 5, 3, 6, 4, 6, 11, 5, 11, 1, 13, 9, 7) and I get my guesses by: v = -log((c(czI01, czI02) - c(czV01, czV02))/c(czI01, czI02))/c(czT01, czT02) vguess = mean(v) cguess = var(v)/vguess^2 It's also possible that I'm doing something else completely wrong, but my results seem reasonable so I haven't caught it.

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  • How can Google publish Dalvik as Java-language compatible since Java is a trademark?

    - by Bruno Chagas
    According to this thread Java and JVM license You can write a compiler that implements the Java Language Specification or write a JVM that implements the Java Virtual Machine specification, but when you officially want to call it "Java", you have to prove it is compatible by passing the tests of the TCK (technology compatibility kit) and pay for a license from Oracle. So, how can Google (or any other java implementation for that matter) claims that Dalvik is a Java virtual machine?

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